Abstract: A current limiting circuit is electronically connected between a power source and a load, and comprises a MOSFET having a drain, a gate, and a source, a first operational amplifier, a voltage-limiting circuit, and a first transistor having an emitter, a base, and a collector. The drain is connected to the power source, the source is connected to the load and is grounded, and the gate is connected to the voltage-limiting circuit. The emitter is connected to the voltage-limiting circuit, the base is connected to the first operational amplifier, and the collector is grounded. The first operational amplifier detects an output voltage of the load to control a drain current of the MOSFET for protecting the MOSFET from being overloaded, and the current limiting circuit has no current limiting resistor, such that power consumption is reduced.

Abstract: An isolated signal transmitting device, an isolated signal transmitting circuit and an isolated receiving circuit thereof are provided to transmit analog signals and digital signals not commonly grounded. The isolated signal transmitting device adapts one current loop for transmitting the analog signals and the digital signals in two opposite directions. The isolated signal transmitting device has two optical couplers to isolate an input and an output of the isolated signal transmitting device not commonly grounded, and the coupled analog signals and the coupled digital signals have respective outputs. Then a user can determine whether the signal is digital or not according to the respective output.

Abstract: The present invention is a switched-mode power supply for providing a stable output voltage. An excitation winding, a vice-output winding and an active snubber circuit are connected to a primary side of a flyback-based transformer. A main-output winding is connected to a secondary side of the transformer. A primary-side PWM controller and a secondary-side PWM controller are respectively connected to the primary side and the secondary side of the transformer. By a time-shared-energy-transfer method, the main-output winding and the vice-output winding are controlled to sequentially extract demand electricity from the transformer during a same switching cycle. Additionally, by a time-shared-energy transformation, the output voltage on the secondary side of the transformer is stabilized to be provided between a stable minimal voltage and a preset higher voltage for satisfying a heavy-loading status and a light-loading status.

Abstract: The present invention is a switched-mode power supply for providing a stable output voltage. An excitation winding, a vice-output winding and an active snubber circuit are connected to a primary side of a flyback-based transformer. A main-output winding is connected to a secondary side of the transformer. A primary-side PWM controller and a secondary-side PWM controller are respectively connected to the primary side and the secondary side of the transformer. By a time-shared-energy-transfer method, the main-output winding and the vice-output winding are controlled to sequentially extract demand electricity from the transformer during a same switching cycle. Additionally, by a time-shared-energy transformation, the output voltage on the secondary side of the transformer is stabilized to be provided between a stable minimal voltage and a preset higher voltage for satisfying a heavy-loading status and a light-loading status.